1. Field of the Invention
The invention relates to a method for reactivating a catalyst for producing ε-caprolactam. The invention also relates to a method for producing ε-caprolactam from cyclohexanone oxime using a reactivated catalyst.
2. Description of the Related Art
One of known methods for producing ε-caprolactam is a Beckmann rearrangement reaction of cyclohexanone oxime in the presence of a zeolite catalyst. Since the activity of the catalyst slowly decreases with time during use, Japanese Patent Application Laid-Open (JP-A) No. 5-9180 has proposed to allow the used catalyst to contact ammonia for reactivating the catalyst, while JP-A No. 2003-320260 has proposed for the reactivation to allow the used catalyst to contact an aqueous solution containing a quaternary ammonium compound and/or a lower alkylamine and ammonia.